CVE-2026-66853 in Gitea
Summary
by MITRE • 10/15/2026
Gitea's user organization-list API includes Limited-visibility organizations for authenticated restricted accounts without applying the visibility restriction enforced by the single-organization endpoint. A restricted user can list a known user's public organization memberships and retrieve limited organizations' names, descriptions, and avatars. This exposes organization metadata that should be hidden from the requesting account.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability identified in Gitea represents a critical access control failure within its API layer, specifically affecting how authenticated users interact with organizational data. In secure software architecture, visibility restrictions are paramount for maintaining privacy boundaries between different user groups and organizations. The core technical flaw lies in the inconsistent implementation of authorization checks across two distinct endpoints: the single-organization endpoint and the organization-listing endpoint. While the former correctly enforces strict visibility policies to prevent unauthorized access to private or limited-scope organizational data, the latter fails to apply these same restrictions when processing requests from restricted accounts. This discrepancy creates a logic error where an attacker can bypass intended security controls by leveraging the list functionality instead of direct object retrieval.
From a technical perspective, this issue stems from insufficient input validation and authorization checks within the organization-listing API handler. When an authenticated user with limited privileges sends a request to enumerate organizations associated with another known public user, the system retrieves metadata such as organization names, descriptions, and avatars without verifying whether the requesting account has permission to view those specific entities. The application logic assumes that because the target user is public, their organizational memberships are also publicly accessible or at least visible to any authenticated peer. However, this assumption ignores the granular visibility settings assigned to individual organizations, which may restrict access to members only or a select group of users. Consequently, the API returns sensitive metadata for limited-visibility organizations that should remain hidden from the requesting account.
The operational impact of this vulnerability is significant in terms of information disclosure and reconnaissance capabilities available to malicious actors. By exploiting this flaw, an attacker can map out the organizational structure of their targets without needing elevated privileges or direct membership in those groups. This exposure facilitates further attacks by revealing internal team compositions, project affiliations, and potentially sensitive business relationships encoded within organization descriptions. In enterprise environments where Gitea is used for source code management, such information leakage can aid social engineering campaigns, targeted phishing efforts, or the identification of high-value targets for subsequent exploitation attempts. The ability to enumerate limited organizations effectively neutralizes the privacy controls intended by system administrators and users alike.
This vulnerability aligns with CWE-284 Improper Access Control, as it involves a failure to enforce proper restrictions on authenticated users attempting to access resources they are not authorized to view. Furthermore, from an offensive security perspective, this behavior is consistent with ATT&CK technique T1087 Account Discovery, where adversaries gather information about accounts and their associated groups or organizations within a networked environment. The exploitation of this flaw allows for the passive collection of intelligence that can be used to plan more sophisticated attacks against the target infrastructure.
To mitigate this risk, immediate action is required to synchronize access control logic across all API endpoints handling organizational data. Developers must ensure that every request to list or retrieve organization information undergoes a rigorous authorization check that validates the requester's permissions relative to each specific organization's visibility settings. This includes verifying whether the requesting user has explicit membership in limited-visibility organizations before returning any metadata. Additionally, implementing comprehensive unit tests for edge cases involving mixed visibility levels will help prevent regression of this issue. Administrators should also consider enabling detailed audit logging to monitor access patterns and detect potential enumeration attempts until a patch is deployed. Regular security code reviews focusing on authorization logic consistency across different API methods are essential to maintain robust access control mechanisms in the application.